Power hammers, such as hydro-mechanical hammers, typically have an actuation system and a tool assembly that includes a work tool and a retention system for holding the work tool within the hammer. In many power hammers, the actuation system drives a piston against a first end of the work tool (e.g., using a working fluid, such as compressed air or a hydraulic fluid), thereby providing a force on the work tool for breaking up work material, such a rock, concrete, etc. To prevent the work tool from being forced out of the hammer during operation, the retention system typically includes one or more components that engage certain features of the work tool to provide a hard stop in the direction of tool actuation.
One problem associated with conventional work tools is that the features of the work tool that engage the retention system of the hammer can create weak points in the tool's structure. For example, during operation, these weak points receive high impact forces by engagement with the retention system under force of the pistons. The geometry of the work tool's retention features can induce stress concentrations near these features during operation, which can lead to the sudden or eventual failure (e.g., breakage) of the work tool. In some situations, a work tool may fail long before its useful life is consumed, thereby incurring a wasteful cost.
One type of tool retention system is discussed in U.S. Pat. No. 7,832,495 to Pillers II (the '832 patent) that issued on Nov. 16, 2010. The '495 patent discloses a tool assembly of a hydraulic hammer having a housing and a chamber defined in the housing for housing a piston and a work tool. The work tool includes a shaft, a retaining flange, and a tip. The shaft passes through a tool retention member having a central aperture with a diameter smaller than the flange to limit the stroke travel of the tool during operation. The housing includes an engaging structure having a socket portion with four projections for receiving a plug portion of the work tool. The plug portion of the work tool includes four lugs that engage beneath the projections when the plug portion is inserted into the socket portion and rotated with respect to the socket portion. A tool stop is included in the socket portion to indicate when sufficient rotation has been achieved. Two set screws are used to secure the plug portion to the socket portion for preventing relative rotation of the work tool with respect to the housing.
While the system of the '495 patent may be effective to secure a work tool within a hydraulic hammer, it may not be usable with different types of hammer designs or work tool designs.
The disclosed hammer work tool is directed to overcoming one or more of the problems set forth above.